Electronic musical instrument



July 23, 1957 Filed NOV. 2, 1951 J. M. HANERT souzcs 0F VIBRATO FREQUENCY (FIG-5) ELECTRONIC MUSICAL INSTRUMENT 3 She ets-Sheet 1 VI BIZATO FREQUENCY SOURCE OF United States Patent ice ELECTRONIC MUSICAL INSTRUMENT John M. Hanert, Des Plaines, Ill., 'assignor to Hammond Organ Company, a corporation 'of Delaware Application November 2, 1951, Serial No. 254,512

8 Claims. (Cl. 84--1.01)

My invention relates generally to an electronic musical instrument which is not only economical to manufacture but is especially well adapted for the playing of organ music with a full organ type of registration in which the brilliant effect of octave couplings is tonally prominent. While this organ is not capable of producing all the various solo and accompaniment octave coupling effects in which the various -'octavely-rel'ated tone sources are found in varying degrees of intensity, as in large pipe organs, it nevertheless does produce the very important full organ tone which is so important for accompanying the congregational singing of hymns, anthems, and for other liturgical purposes.

.In general, electronic organs, as at present on the market, utilize an oscillator, or a frequency dividing stage for each note within the gamut of the instrument. As 'a result, such organs may contain as many as eighty vacuum tube oscillators for the generation of the tone signals.

It 'is one of the objects of my invention to greatly reduce the number of oscillators required without, in any appreciable way, impairing the usefulness of the instrument in the rendition of popular and classical selections.

It is a further object of my invention to provide an improved electronic organ in which coupled octaves may be employed to enrich the tonal output of the instrument.

Other objects will appearfrom the following description, reference being had to the accompanying drawing in which:

Figure 1 is a schematic wiring diagram of a preferred form of oscillator;

Figure 2 is a schematic wiring diagram of a second form of oscillator which may be employed;

Figure 3 is a schematic wiring and block diagram of means for producing vibrato signals;

Figure 4 is a schematic Wiring diagram of a representative portion of an electronic organ employing octave couplers;

Figure 5 is a block diagram of a complete instrument employing oscillators of the type shown in Fig. l and a keying and octave coupler mechanism of the type shown in Fig. 4;

Figure 6 is a schematic wiring and block diagram of a modified form of the invention.

Referring to Fig. 1, the oscillator 28 comprises a triode 30 having an adjustable tuning circuit including a capacitorC42 and a variable inductance L34 connected between a terminal S and a terminal 36. The terminal 36 is connected to the control grid 38 of triode 30 through a capacitor C40. The cathode 42 is connected to a tap on the inductance L34 while the plate 44 is connected to a terminal K through an attack resistor R46 which has a resistor R48 and capacitor C50 in series across its terminals. The plate 44 is connected to ground through an attack and decay capacitor C52. The control grid 38 is connected to a terminal V through a grid resistor 2,800,047 Patented July 23, 1957 2 R54 while the terminal 36 is connected through a decoupling resistor R56 to a terminal F.

The terminal V will be connected to one of the terminals 104 or 105 of the vibrato apparatus (Fig. 3) depending upon the manner in which the oscillator is to be used, as will appear hereinafter.

The frequency of oscillation of the oscillator 30 may be decreased one semitone by connecting a capacitor C58 between the cathode and terminal S and for this reason the capacitor C58 is shown as connected between cathode 42 and a tuning terminal T so that by a switching means, not shown in Fig. l, T may be connected to S whenever it is desired to lower the pitch of the oscillator by one semitone.

The oscillator shown is adapted to be keyed (rendered operative) by supplying plate voltage to the terminal K and will have its frequency shifted to introduce the vibrato effect by having a vibrato frequency signal impressed upon the terminal V. The signal which appears upon the terminal F is of flute-like character, that is, it is substantially sinusoidal. On the other hand, the signal appearing at the terminal S, across a resistor R60 which may be common to a plurality of oscillators, will be ver complex and rich in harmonics so that, by the use of suitable filtering meshes, tone qualities of the string and reed families may be derived therefrom.

In such forms of the invention in which the signal is to be keyed, requiring a continuously operating tone signal generator, the oscillator shown in Fig. 2 may be employed. This oscillator 29 comprises a triode 70, the control grid of which is connected to the V (vibrato) terminal through grid resistor R54.

The plate of the triode 70 is connected to ground through a blocking capacitor C53 and coupling resistor R71, and is connected to a 8+ terminal through a load resistor R72. The cathode 74 is connected to a terminal T1 by a capacitor C73, and is connected to a tap on a variable inductance L76 which has a capacitor C78 in parallel therewith. One end of the resonant circuit provided by L76 and C78 is connected to the grid of the triode 70 through a capacitor C80. The other terminal of the resonant circuit is connected to ground. The string-quality signal is derived from a terminal S1 which is connected to the junction of C53 and R71.

The apparatus for producing vibrato modulating frequencies of several different phases is shown in Fig. 3 as comprising a phase shift oscillator consisting of a triode 92 the cathode of which is connected to ground and the plate of which is connected to a B+ terminal of the power supply through a load resistor R94. A multisection phase shifting mesh is connected between the plate and grid of the triode 92 and comprises a plurality of series capacitors C96, and shunt resistors R98. Each of the resistors has one end connected to a 2.5 terminal and its other end connected to one of the junctions between capacitors C96. This phase shifting mesh has a terminal connected to the plate of triode 92 and connected to an amplifier and phase inverter 102 having terminals 104 and 105 at which the vibrato signal appears in opposite phase. The other terminal 106 of the mesh is connected to the grid of triode 90 by a resistor R106.

In Fig. 4 there are shown three oscillators 28 of the type shown in Fig. l which are intended to be representative of all the oscillators employed in the instrument as tone generators. Alternate octaves of oscillators have their V terminals connected to a conductor 110 which is connected to terminal 104 of the vibrato apparatus while the oscillators of intermediate octaves have their V terminals connected to the terminal 105 by a conductor 111 of the vibrato apparatus at which the vibrato signal appears in phase opposite to that of the signal on termi- 3 nal 104. The F terminals of all of the oscillators are' connected to a conductor 112 which transmits the signal to tone and volume controls and an amplifier 114.

In a similar way, the S terminals of all of the oscillators are connected by conductor 116to the tone and volume controls and amplifier 114. The conductor 116 is connected to ground by a resistor R60 so that this resistor need not be included in each of the oscillators. put of the amplifier is transmitted to a speaker 118.

Each of the playing keys 120 operates three tuning switches 122,123, and 124 and, in addition, operates three keying switches 126, 127, and 128, the switches being so constructed that upon depression of one of the keys 120 its tuning switches 122, 123, and 124 will be closed prior to the closure of its keying switches 126, 127, and 128. Thus the oscillator is tuned to the required pitch prior to being rendered operative by closing its keying switch.

' It'will be noted that the keying switches are adapted to connect the K terminals of the oscillators to one of three bus bars 130,131, and 132 which are connected to a terminal of the plate current supply indicated as a terminal 13+. The tuning switches are adapted to connect the T terminals of the oscillators to one of the bus bars 134,135, or 136 which are connected to each other and to the conductor 116 leading to the S terminals.

' Referring to Fig. 1, it will be apparent that when the S terminal of an oscillator is connected to its T terminal the capacitor C58 will be in parallel with a portion of the inductance L34. The value of C58 is chosen such that the pitch of the tone signal produced by the oscillator will be lowered by a semitone whenever its T and S terminals are connected. It will be noted that the oscillator for the notes G2 and G2# has its T terminal connected not only to the switch 122 under the key G2 but also to one pole of a switch 138 which when closed connects the T terminal to the switch 124 operated by the key G1. Likewise the K terminal of the G2G2# oscillator 28 is connected to one pole of a switch 139, the other pole of which is connected to switches 128 beneath the G1 and G1# keys 120. The switches 138 and 139 are adapted to be operated by a suitable 4 octave coupler tablet 140.

The T terminal of the G2G2# oscillator is also connected to one pole of an octave coupler switch 144 which is in series with the switch 123 beneath key G3. The K terminal of the oscillator G2G2# is connected to one pole of a switch 146, the other pole of which is connected to switches 127 beneath keys G3 and G3#. The switches .144 and 146 of all of the oscillators are adapted to be closed by the operation of a 16' coupler tablet 148. For the sake of simplicity all of the wire connections to the various coupler switches (138, 139, 144, and 146) are not shown but the connections for all oscillators of the instrument will be the same as shown for the oscillator G2--G2# except, of course, that the oscillators for the highest octave of the instrument will not have any switches 138, 139 for the 4' coupler, nor will the lowest octave of oscillators have switches 144 and 146.

For example, when the key G2 is operated, closure of its switch 122 will tune the G2G2# oscillator to the pitch G2. Closure of its switch 123, assuming that the .16 coupler tablet 148 has been operated, will result in tuning the G1-G1# oscillator to the pitch G1. Also, assuming that the 4 coupler tablet 140 has been operated, closure of switch 124 will result in tuning oscillator .G3G3# to the pitch G3. After switches 122, 123, and 124 have been closed switches 126, 127, and 128 will be closed thereby connecting the 18+ terminal to the'K terminals of the three oscillators shown. The oscillators will then commence oscillating and continue to supply flute-type and string-type signals to the conductors 112 and 116 respectively. The signals are thus supplied to the tone and volume controls and amplifier 114 as long as the key is held depressed. Due to the provision of the resistor R46 and capacitor C52 the attack and decay of The outthe tone produced will be devoid of objectionable transients. The capacitor C50 and resistor R48 are provided to make certain that the oscillator will commence oscillating substantially immediately upon connecting the terminal K to the 13+ supply, even though the vibrato voltage applied to the grid happens to be negative at the instant the keying switch (e. g. switch 122) is closed.

In constructing an instrument having the tuning and keying circuits of the kind shown in Fig. 4, it is preferable to split the instrument into a treble section and a bass section, generally in the manner indicated in Fig. 5, that is, between the notes G3# and A3. Alternate octaves of oscillators should have their V terminals connected to the terminal 104 of the vibrato apparatus while the intermediate octaves of oscillators should have their V terminals connected to the terminal 105 of the vibrato apparatus 102, but for simplicity of illustration all oscillators below the split are shown as having their V terrninals connected to the terminal 104, and those above the split as having their V terminals connected to the terminal 105, when switches 147 and 149 are closed.

The output of all the bass section oscillators is supplied to tone and volume controls 150 while the output of the treble register oscillators 28 is supplied to tone and volume controls 152, which may be similar but usually will differ from the controls 150. Over-all volume or expression controls may be operated by independent actuators or by a common actuator.

The signals, as modified by the tone and volume controls, are supplied to independent preamplifiers 154, 155, which are coupled to independent power amplifiers 156 and 157, the latter supplying speakers 158 and 159 respectively.

All of the tuning and keying circuits for the instrument diagrammatically illustrated in Fig. 5 are the same as those shown in Fig. 4, although in some instances it may be desirable to omit, or to provide manually operated switches for breaking, some of the coupling connections which cross the split between G3# and A3.

By splitting the instrument illustrated in Fig. 5, the organist has at his command substantially the equivalent of a two manual organ, since he may change the registration of the bass and treble sections independently and may utilize the vibrato on either or both sections.

In Fig. 6 is illustrated a modified form of the invention in which oscillators 29 such as shown in Fig. 2 are employed. It will be recalled that these oscillators operate continuously while the instrument is being played and that the output signals of the oscillators are keyed to the output system. Three representative oscillators for the octave interval notes G1 to G3# are shown. The oscillators are connected to the vibrato apparatus 102 in the same manner as shown in Fig. 4 and the key-operated switches and octave-coupler switches are operated and connected in the same manner as those illustrated in Fig. 4. However, instead of having the switches 126, 127, and 128 connected to the K terminal of the oscillator of Fig. 1, they are connected through decoupling resistors R162 to the S1 terminals of the oscillators of Fig. 2 type. The resistors R162 are of relatively high value so that when the octave couplers are used and octaves are played on the keyboard of the instrument the amplitude of the signal from a single oscillator will be increased substantially.

It will be noted that the switches 126, 127, and 128, when closed, connect the S1 terminals of their associated oscillators with bus bars 164, 165, and 166, that these bus bars are connected together, and that the signals appearing thereon are supplied to tone and volume controls 168 and are transmitted to an amplifier 169 and a speaker 170.

In each of the embodiments of the invention disclosed herein one oscillator serves as a signal source for tones of adjacent semitone intervals. The number of oscillators required for an instrument is thus reduced by substantially one-half thereby making it possible to produce the instrument at a relatively low cost.

It will be understood that in some organs it may be desirable to omit the use of the coupler switches, such as switches 144, 146, 138, and 139, in which event the full organ effect will be present at all times. In other instances these switches may be omitted and means provided to render the serially connected switches 123, 124, 127, and 128 effective or ineffective, as desired, by suitable mechanical means.

The underlying octave coupling principles of the invention may also be utilized in instruments in which adjacent oscillators are tunable through overlapping ranges not only to produce a chorus effect but also to make possible a simultaneous production of the semitone intervals, as for example in the instruments disclosed in my copending application, Serial No. 254,574, filed November 2, 1951, Patent No. 2,681,585, granted June 22, 1954.

The oscillators disclosed herein are disclosed and claimed in my copending application Serial No. 224,276, filed May 3, 1951, now abandoned, and in the copending application of Laurens Hammond, Serial No. 96,107, filed May 28, 1949. The use of vibrato signals of opposite phase in octavely related oscillators is disclosed and claimed in my copending application, Serial No. 223,376, filed April 27, 1951.

While I have shown and described several embodiments of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument having an output system, a first electronic oscillator, a second electronic oscillator having a tuning circuit to change its pitch, a keyboard having a first key and a second key spaced an octave from the first key, first switch means operated by the first key to couple the outputs of the first and second oscillators to the output system, switch means operated by the second key to couple the output of the second oscillator to the output system, a switch in the tuning circuit of the second oscillator and operable by the first key to change the pitch of the second oscillator, an additional switch operable by the second key, and conductors connecting said switches in parallel.

2. In an electrical musical instrument having an output system, a first electronic oscillator, a second electronic oscillator having a tuning circuit to change its pitch, means coupling the outputs of both oscillators to the output system, a keyboard having a first key and a second key spaced an octave from the first key, switch and circuit means controlled by the first key to render operative the first and second oscillators, switch and circuit means controlled by the second key to render the second oscillator operative, a switch in the tuning circuit of the second oscillator and operable by the first key to change the pitch of the second oscillator, an additional switch operable by the second key, and conductors connecting said switches in parallel.

3. In an electrical musical instrument having an output system, a first electronic oscillator, a second electronic oscillator having a tuning circuit to change its pitch, a keyboard having a first playing key, a second playing key spaced an octave from the first key and means operated by the first key to cause transmission to the output system of the signals produced by the first and second oscillators, means operated by the second key to cause transmission of the signal from the second oscillator to the output system, a switch in the tuning circuit of the second oscillator and operable by the first key to change the pitch of the second oscillator, a second switch operable by the second key, and conductors connecting said switches in parallel.

4. In an electrical musical instrument having an output system, a first electronic oscillator, a second electronic oscillator having a tuning circuit to change its pitch, a keyboard having a first key and a second key spaced an octave from the first key, switch means operated by the first key to couple the outputs of the first and second oscillators to the output system, switch means operated by the second key to couple the output of the second oscillator to the output system, and circuits including switch means operable by the keys to render the tuning circuit of the second oscillator operative to tune the second oscillator to the same pitch upon operation of either key.

5. In an electrical musical instrument, the combination of a plurality of electronic oscillators each having means capable of tuning it to either of two frequencies corresponding to adjacent semitone pitches of the tempered musical scale, a plurality of playing keys, a plurality of busbars, means connecting the busbars to sources of constant direct current potential, a plurality of switches operated by each of said keys for making connections with said busbars, one to three of said switches being effective with said tuning means to tune one to three octavely related oscillators respectively to pitches differing by a semitone from the normal pitch of the oscillators, others of said switches being operatble to connect one to three octavely related oscillators to the output system of the instrument, and octave coupler switches selectively operable to couple certain of the switches under the keys associated with one oscillator with corresponding switches operated by keys associated with octavely related oscillators.

6. In an electrical musical instrument, the combination of a plurality of octavely related oscillators each having a terminal which when connected substantailly to ground potential tunes the oscillator to a frequency differing by one semitone from the pitch at which it normally operates and having a keying terminal which when connected to a source of operating potential renders the oscillator operative, a pair of playing keys associated with each oscillator, means operable by one of the playing keys of a pair to tune its associated oscillator to a pitch difiering by one semitone from its normal pitch, means operable by each of the pair of keys associated with each oscillator to connect the keying terminal of such oscillator to said source of operating potential, and selectively operable octave coupler switches for respectively rendering said keys operative to tune the higher and lower pair of octavely related oscillators to corresponding octave related pitches and to render said octavely related oscillators operative.

7. In an electrical musical instrument having an output system and a plurality of playing keys, the combination of a plurality of electronic oscillators, tuning means associated with each oscillator to tune it to any of at least two different pitches of the musical scale, switches operable by at least some keys to cause the tuning means of several octavely related oscillators to tune them to octavely related pitches, and additional means operated by each key to cause signals produced by the oscillators tuned by the operation of such key to be transmitted to the output system, whereby octave coupler effects may be obtained by the use of fewer oscillators than the number of tones of different pitch which may be produced.

8. In an electrical musical instrument having an output system, a first electronic oscillator, a second electronic oscillator normally tuned to a pitch differing by an octave from that of the first oscillator and having a tuning circuit to change its pitch by at least one semitone, means coupling the outputs of both oscillators to the output system, a keyboard having a first key and a secconductors connecting said last named two switches in 0nd key spaced an octave from the first key, two switch parallel.

and circuit means controlled by the first key to render operative the first and second oscillators, additional switch References Cited 1n the file of this Patent and circuit means in parallel with one of said two switch 5 UNITED S A PATENTS and circuit means and controlled by the second key to 2,276,390 Hanert Man 17, 1942 render the second oscillator operative, a switch in the tuning circuit of the second oscillator and operable by 24O3090 Larsen July 1942 2,505,182 Haller et al. Apr. 25, 1950 the first key to change the pitch of the second oscillator, an additional switch operable by the second key, and 10 

